1. Field of the Invention
This invention relates generally to an avalanche victim locating transceiving apparatus for locating buried victims by a searching survivor and, more particularly, it relates to an avalanche victim locating transceiving apparatus for locating buried victims by a searching survivor which provides both directional and distance readouts to the searching survivor.
2. Description of the Prior Art
Avalanches pose an extremely grave danger for skiers, climbers, military personnel, and others in mountain regions during winter and spring. Death or serious injury can result when a person is buried in snow unless rescue is quickly effected. Rescue is difficult because a person buried in an avalanche cannot be seen, may be moved by the avalanche away from the last visible position, and cannot easily be located. Suffocation, hypothermia, and cardiac arrest, coupled with shock, become more likely the longer the victim is buried. The amount of time spent in locating a victim is an important factor in the probability that the victim will not survive or will be severely injured.
In an attempt to address these problems, electronic locating systems are increasingly being used, for example, by the ski industry, snowmobilers, and the military. With one type of system presently in use, each member of a group exposed to avalanche danger is supplied with a continuously energized, battery powered radio transceiver unit operating continuously in a transmitting mode. With these known systems, continuous transmission is relied upon to assure that transmission occurs when a victim is buried. If part of the group is buried in an avalanche, the remaining members switch their units to a receiving mode and attempt to locate buried individuals by variations in received signal strength.
This type of system has serious drawbacks. Since the older units had to be easily portable and battery weight was limited, the use of high power alarm signals was impractical. These conventional units merely provided a non-directional signal. In order to find a buried victim, it is necessary to move about, preferably in a grid pattern, while attempting to detect increases and decreases in signal strength. This can be difficult and time consuming, particularly in the unfavorable terrain common to avalanche sites. The difficulty is compounded by the fact that survivors are often confused or in shock. In addition, if multiple victims are buried, the region of maximum signal strength may not coincide with the location of a victim. In the prior art, power consumption and the necessity for continuous transmission prevent the use of an audible alarm that would be useful when a survivor is in relatively close proximity to a victim.
In an effort to overcome the shortcomings of the prior art, the Allsop et al, U.S. Pat. No. 4,850,031, describes an avalanche victim locating system having a trigger provided by light sensitive elements on the user, or by a signal transmitted from a survivor. A microprocessor control synchronizes VHF information signal transmission and burst microwave transmission from a victim as well as received signal processing by a survivor. A directional multiple antenna array is switched to provide directional signals displayed to the survivor and is extended when the apparatus is opened.
While the avalanche victim locating device of the Allsop et al patent overcomes many of the problems associated with the prior art, the device of the Allsop et al patent creates additional difficulties which must be addressed. First, with the Allsop et al patent's device, it is not possible to determine exactly the distance between the buried victim and the searching survivor. Second, the device of the Allsop et al patent relies on sensors to activate the unit to a transmitting mode. If the sensors are defective or become faulty, there is a chance that the transmitting mode will never be activated. Third, even if the Allsop et al patent's device can be remotely activated by a rescuer, the rescuer must have the same device in order to activate the transmitting mode. If rescuers are using a different type of avalanche rescue device, they will not be able to activate the transmitting mode and the buried victim will not be able to be located. Finally, the device of the Allsop et al patent relies on microwave technology which requires the size of the rescue equipment to be quite large.
Accordingly, there exists a need for an avalanche victim locating transceiving apparatus for locating buried victims by a searching survivor which provides both directional and distance readouts to the searching survivor. Additionally, a need exists for an avalanche victim locating transceiving apparatus for locating buried victims by a searching survivor which provides improved rescue times and decreases the amount of time the buried victim remains buried. Furthermore, there exists a need for an avalanche victim locating transceiving apparatus for locating buried victims by a searching survivor which provides dual visual/audible functions for directional and versatility and backup redundancy for user confidence in all weather conditions. Further yet a need exists for avalanche victim locating transceiving apparatus for locating buried victims by a searching survivor which provides an efficient, tuned transmitter which automatically switches from a search mode to a transmit mode in case of rescuers being caught in a secondary avalanche while trying to locate the buried victims.